Hello! For the "In which your daughter sees the boundaries between two worlds" ending, you need to run the Mountain Final Challenge Event (unlocked by scaling the smaller mountain during Summer or Autumn)
xx SPOILERS FOR MOUNTAIN FCE AHEAD xx
At the top of the mountain, when facing the knight at the summit with the Dreamer, attempt to dissuade him (not fight or stand your ground).
This is one of multiple endings attributed to the Mountain Final Challenge.
xx END OF SPOILERS xx
Hope that helps!
-Zaozoruzhna